Drop hammer die and method of forming same



July 2, 1940. w. H. J. FITZGERALD Er AL 2,206,812

DROP HAMMER DIE AND METHOD OF FORMING SAME Original Filed July 8, 1937 I A Figi bym MI M ATTYS.

Patented July 2, 1940 UNITED l STATES DROP HAMMER DIE AND METHOD 0F rom/[ING SAME "William H. J. Fitzgerald, deceased, late ofBraintree, Mass.,

executrix, Braintree, Mass., and Reginald Fitzgerald, Braintree, Mass.,

by Josephine" M. Fitzgerald,

assignors to Pneumatic Drop Hammer Company, Braintree,

Mass., a corporation of Massachusetts original ,application July s, 1937, serial No.

152,544. Divided and this application `May 9, 1939, Serial No. 272,585

2 claims. (o1. 22-203) This invention relates to improvements in drop hammer construction nwhich the hammer and anvil are provided with complementary dies for shaping ductile sheet metal or the like and in A, which the die faces of the hammer and anvil are complementary to each other.

4p" Furthermore, the lowering of the cold hammer upon the molten metal chills the upper surface In usual drop hammer constructions of this type `the anvil die is of hard metal and the hammer die of relatively softer metal which is cast upon the anvil die so that the die faces are exactly complementary to each other. The anvil die may be of iron or steel suitably surfaced to conform to the article to be shaped, or may be of such composition as zinc or bronze cast in aplaster of Paris mould presenting a face com` plementary to that of the article to be dieshaped- In either case the anvil die may be placed upon the anvil ofthe drop hammer and the hammer die cast upon the anvil die. The soft metal, such as lead, of the anvil die is relatively cheap and when worn or injured may be readily re-cast to produce a duplicate of the original die or used for the purpose of making other forms of hammer dies in like manner.

In previous processesof casting a hammer die a plate having dovetail recesses on its under surface has been secured to the under face of the hammer, wall built up around the anvil die extending above the upper surface thereof a distance equal to the depth of the desired hammer die; the chamber within the frame thus formed then filled with molten metal and the hammer lowered until the metal is forced into the dovetail recesses in the plate and the hammer permitted to remain in such position until the `metal is cool. This process is objectionable for the reason that the pressure of the hammer upon the molten metal lling the chamber of the frame frequently causes the excess of molten metal to be squirted out thus endangeringthe operator.

thereof. l

Dies formed in thismanner are `objectionable in that it is very difcult to remove the soft metal die from the plate to which it is secured which is `usually accomplished by` the insertion of wedges the grooves and during the detachment of the soft metal die distortions are pro duced which render it unfit forlfurther use.

One of the objects of the invention is to produce a hammer diein which these objections will be avoided and to produce a hammer die which can be readily removed from and re-assembled upon the hammer with accuracy.

Another object of the invention is to provide complementary anvil and hammer dies of the character above described of much greater size than have heretofore been produced which can" be employed in shaping large sheets of metal such as are employed as fenders for automobiles, and other parts of automobiles, metal aeroplane wings, or other large areas of sheet metal and the like, and particularly those in `which the dies are of irregular contour and of unsymmetrically distributed weight.

The present invention while of general use is particularly adapted for drop hammers of large capacity of the character disclosed in our previous prior application Serial No. 152,544 iiled July, 1937, of which the present application is a division.

`An illustrative embodiment of the invention is shown in the accompanying drawing, in which,

Fig. l is a detail view of the lower portion of a drop hammer construction of the character disclosed in our prior application showing the hammer and -anyil in vertical section on line I-l Fig. 2 and illustrating the manner in which the hammer die is castlupon the hammer; and) 2 is a plan View of the hammer onstruction illustrated in Fig. 1.

The drop hammer construction illustrated in Fig, 1 comprises a base l having an anvil 2 and side frames 3 which are mounted upon and eX- tend upwardly from the base and are provided with suitable guides 4 for the hammer. The preferred form of hammer which is illustrated herein as adapted for dieshaping long articles of considerable width comprises a body 5 of rectangular form having` a at under face E and with guiding members 1 which extend both upwardly and downwardly from said body and have suitable grooves to engage the guides 4 on the frame. `The hammer is provided with `a central upwardly extending integral boss 8 with vertical integral webs 9 extending radially to and merging into the guides 1. The ends of the hammer are` provided with extensions It which project outwardly between and beyond the respective pairs of guides 4 and the lifting forces for raising the hammer are applied to such extensions from beneath. The boss 8 is provided with a central bore having a screw` threaded wall to receive `an abutment screw ll having an enlarged head adapted to engage suitable cushioning` mechanism and a lock nut I2 whih is mounted on the screw ll and engages the upperend of the boss 9 serves to retain the abutment `member in adjusted positions.

Iii.

In order to prevent displacement of the anvil die upon the anvil by the repeated shocks of the hammer, the upper surface of the anvil desirably is provided with series of parallel grooves I3 extending transversely and longitudinally of the anvil over a somewhat larger area than the su;- face oi the anvil die; the outer grooves I4 being considerably wider than the other grooves and adapted to receive the lower end ofk vertical frame members I5 which extend above the surface of the die the necessary distance to provide the desired depth for the hammer die.

The anvil die may be constructed in the usual manner by surfacing or die cutting in a block of hard metal or by casting the anvil die in a suitable mould of plaster of Paris or the like, having a lower face corresponding to the desired contour of the die. The anvil die may then be reversed and placed upon the anvil and surrounded by the frame l5 in the manner above described.r f One of the objects of the invention as above described is to provide a hammer die which is cast directly upon ther hammer and so connected to it that it can be readily removed and replaced. This is accomplished by providing the lower horizontal body of the hammer with a sufficient number of properly distributed holes to receive anchoring bolts iii, the heads of which depend well below the lower face of the hammer and the upper ends of which are provided with nuts il which support the bolts in place during the castingof the upper die and thereafter serve detachabfly to secure the hammer die to the hammer. f

In order to provide for casting the hammer die upon the hammer, the hammer is provided with a plurality of properly spaced sprue holes i8 of any desired number according to the area of the hammer. These sprue holes are of upwardly tapered', preferably conoidal, form. The hammer thus prepared-wtih sprue holes and with depending bolts is then lowered until it engages or rests upon the upper edges of the frame I5 and the molten soft metal, such as lead, poured in the several sprue holes as nearly simultaneously as possible until the entire chamber of the frame is filled. The heat of the molten metal thus poured through the sprue holes in the hammer is Vtransamitted to the hammer and sufnciently heats the metal of the hammer to reduce the` chilling effect upon the molten metal in the upper portion of the mould lto a minimum, thereby preventing quick coagulation of the metal of the upper surface of the die which would prevent escape of air entrained in the metal as it is poured into the mould.

These sprue holes also permit escape of air from the chamber of the mould or frame thereby insuring complete. filling of said chamber with homogeneous metal.

After the metal of the anvil die thus cast is permitted to cool the hammer is raised and the frame members i5 removed. The hammer die is fixedly or detachably secured to the hammer by the bolts Iii, v but can be readily and quickly removed by cutting on the excess of metal which overflows from the sprue holes in the hammer and then removing the nuts l1 from the bolts I6. Such capability of quick removal of the hammerdie is of great importance where comparatively few number of pieces of sheet metal have to be shaped as other complementary dies which have been constructed in like manner can be readily substituted to form other sheet metal The replacement of the hammer and anvil dies after they have been removed'can be readily accomplished by again seating the anvil die in its v proper position, placing the hammer die upon it and lowering the hammer in which case the bolts it will readily pass through their respective holes in the hammer, and the upwardly extending conical portions lll of the metal of the hammer die will in passing into the conical sprue holes of the hammer aid in accurate positioning of the die upon the hammer. When thus reassembled tlie nutsll. are again replaced upon the bolts It and lset up tightly thereby holding the hammer die in its original position in the hammer. c

It has been mentioned that the anvil die may be cast iny a suitable mould, such as a plaster of AParis mould, and then reversed and placed upon the anvil. When thus placed upon the anvil the under surface of the anvil die will rest upon the ribs intermediate of the grooves I3. When the hammer is raised and dropped the hammer will force the anvil die downwardly so that the metal of the under face of the anvil die will be driven into the recess i3 in the anvil, thereby lxedly positioning the anvil in place and insuring perfect registry with the hammer die. The grooves in the anvil may be so formed that the anvil die can be readily pried loose when it is desired to remove or replace said anvil die.

By reason of the construction of the hammer die and the method of producing it the numerous advantages above pointed out over usual hammer die constructions and processes of producing the same are accomplished. Furthermore, b-y reason'of the construction above described particularly when employed in machines of the character disclosed in our prior application aforesaid,

in which the hammerl is lifted by force applied to the ends of the hammer from beneath, hammers of much larger area and capacity may be constructed and sheet metal shaping work yproduced by drop hammers which has heretofore been considered impossible.

It will be understood that the particular embodiment of the invention shown and described herein is of an illustrative character and is not restrictive of the meaning and scope of the following claims.

Having thus described'the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

l. A drop hammer construction for die forging or die shaping ductile metal comprising an anvil, a ldie mounted on said anvil, and a complementary die of relatively softer metal than that of said anvil diecast directly upon said hammer provided with bolts having their heads embedded in softer metal and extending through said hammer and having nuts engaging the upper side of' the hammer, and also provided with a plurality of upwardly tapering centering projections engaging complementary downwardly tapering walls of apertures in said hammer.

2. The method of` casting a die upon a hammer of a drop hammer construction for producing dieformed work which comprises forming an anvil die, securing the same upon` the anvil with the die face uppermost, enclosing the anvil die in a frame which projects upwardly from the anvil die a distance corresponding to the desired thickness of the hammer die, suspending from the hammer a plurality of bolts having their heads depending suitable distances below the lower face of the hammer, lowering `the hammer upon the upper edge of said frame and lling said frame by pouring throughsprue holes in said hammer molten metal characteristically softer when coo1` than the metal `of said anvil die.

` JOSEPHINE M. FITZGERALD,

Eme'cutz' of the Ldst Will and Testament of William H. J. Fitzgerald, Deceased.

REGINALD P. FITZGERALD. 

